The field of the invention is the architecture of telecommunication networks.
The invention is more particularly aimed at an ordonnancing method, an ordonnancing device, and a multiservice data packet router, all of low complexity, aiming to improve the quality of service by means of which multiservice data packets included in various flows of that network are routed.
It applies in particular to an Internet network.
The “flow” concept used in this document is for example that of the “flow-aware” architecture disclosed in the paper by Bonald et al. “IP traffic and QoS control: the need for a flow-aware architecture”, World Telecom Conference, Paris, 2002.
The Internet has a multiservice vocation and is called upon to support a wide range of services and applications. Two major classes of traffic are distinguished on the Internet, namely real-time traffic (also known as flowing traffic), generally produced by audio or video applications, and data traffic (also known as elastic traffic) corresponding to the transfer of digital documents. The real-time traffic has quality of service requirements corresponding to the requirement for conservation of the signal—the variations of bit rate that characterize the signal produced by the source must be preserved as the signal crosses the network. The quality of service of the data traffic is measured by the document transfer time. That time, or the corresponding average bit rate achieved during the transfer, depends on the whole of the communication chain from the source to the destination. A quality of service objective for an Internet network could be to appear transparent to data traffic without introducing any additional bit rate reduction over limitations introduced elsewhere (server, access networks, user equipment); in this sense the network conserves the bit rate of the data flows.
The Internet public network offers a transport service to user clients in a commercial context. The question of charging is therefore important. The network architecture must provide a return on investment for the operator combined with competitive pricing of the high-quality services demanded by users.
A prior art ordonnancing method that is of low complexity (of order O(1), i.e. independent of the number of flows) known as DRR (standing for “deficit round robin”) is described by M. SHREEDHAR and G. VARGHESE: “Efficient fair queuing using deficit round robin”, IEEE/ACM Transactions on Networking, Volume 4, Issue 3, June 1996, pages 375-385.
The DRR ordonnancing method is based on processing the flows in a cyclic manner, in accordance with the “round robin” principle. This method associates a queue with each flow, each queue, processed cyclically, being authorized to send, in each cycle, packets up to a quota (a quantity of data, for example measured in bytes).
This DRR method ensures a reasonable degree of equity by maintaining a deficit counter for compensating any differences in the packet sizes of the various flows.
Variants of the DRR method associate priority processing with the packets of certain flows.
In particular, the DRR+ method described in the above-mentioned paper enables priority processing of flows sensitive to delay, to the detriment of “best effort” flows. In that method, the priority flows must comply with a contract, i.e. they must not send more than a certain volume of data during a predetermined time period.
Document FR2854296, in the name of the applicant, proposes an ordonnancing method with implicit differentiation of packets to be processed with priority, and consequently offering the advantage of dispensing with that type of contract. However, the ordonnancing method described in that document, which is of the “self-clock fair queuing” type, is of O(log n) order, n being the number of flows to be taken into account, which might seem to be a limitation on its implementation in certain types of routers.
The invention aims to solve the above problems.